Smoking article

ABSTRACT

A smoking article is described in which the smoking article comprises tobacco material wrapped in a paper wrapper to form a tobacco rod, and wherein the paper wrapper has a diffusivity of between about 0.1 cm/s and 0.5 cm/s and a permeability of less than about 15 CU, and a method of manufacturing the smoking article is described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application a National Phase entry of PCT Application No. PCT/GB2020/050782, filed Mar. 24, 2020, which claims priority from GB Patent Application No. 1904890.9, filed Apr. 5, 2019, each of which is hereby fully incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a smoking article and a method of manufacturing a smoking article.

BACKGROUND

Cigarettes and other combustible smoking articles produce smoke which is inhaled by a user. Tobacco is wrapped in a paper wrapper to form a tobacco rod and a filter may be connected to the tobacco rod. Filters can be configured to modify properties of smoke produced by the smoking article, for example, by adding flavorant to the smoke produced by the smoking article.

SUMMARY

According to embodiments of a first aspect of the disclosure, there is provided a smoking article comprising tobacco material wrapped in a paper wrapper to form a tobacco rod, wherein the paper wrapper has a diffusivity of between about 0.1 cm/s and 0.5 cm/s and a permeability of less than about 15 CU.

The paper wrapper may have a diffusivity of between about 0.1 cm/s and 0.3 cm/s.

The paper wrapper may have a diffusivity of between about 0.15 and about 0.25, between about 0.15 and about 0.20, or between about 0.17 and about 0.22 cm/s.

The paper wrapper may have a permeability of less than about 15 CU over at least 50% of the surface area of the paper wrapper.

The paper wrapper may have a permeability of between about 4 and about 12 CU.

The paper wrapper may have a permeability of between about 4 and about 12 CU over at least 90% of the surface area of the paper wrapper.

The paper wrapper may have a permeability of less than about 10 CU, or between about 3 and about 7 CU, over at least 90% of the surface area of the paper wrapper.

The smoking article may comprise a filter.

A pressure drop across the filter may be between about 40 mm Water Gauge (WG) and 180 mm WG.

The filter may comprise a ventilation area.

The ventilation area may provide ventilation of between 40% and 90%.

The filter may comprise filter material having a denier per filament of between 2.5 and 9.

The filter may comprise filter material having a total denier of between 10,000 and 32,000.

The paper wrapper may have a basis weight of between 24 and 36 g/m².

The paper wrapper may have a basis weight of between 27 and 32 g/m².

The paper wrapper may have a basis weight of about 28 g/m².

The paper wrapper may have a basis weight of about 32 g/m².

The paper wrapper may include less than 30% filler by weight of the paper wrapper.

The paper wrapper may include between 15 and 25% filler by weight.

The filler may comprise calcium carbonate.

The paper wrapper may have an opacity of between 60% and 80%, or between 68% and 80%.

The paper wrapper may comprise less than 4% burn additive by weight of the paper wrapper.

The paper wrapper may comprise about 1% burn additive by weight.

The burn additive may be sodium citrate, potassium citrate, or a mixture of sodium citrate and potassium citrate.

According to embodiments of a second aspect of the disclosure, there is provided a method of manufacturing a smoking article, the method comprising forming a tobacco rod by wrapping tobacco material in a paper wrapper having a diffusivity of between about 0.1 cm/s and 0.5 cm/s and a permeability of less than about 15 CU.

The method may further comprise attaching a filter to said tobacco rod.

The method may further comprise providing a ventilation area for allowing ventilation into said filter.

The paper wrapper may have a diffusivity of between about 0.1 cm/s and 0.3 cm/s.

The paper wrapper may have a permeability of between about 4 and about 12 CU over at least 50% of the surface area of the wrapper.

The paper wrapper may have a permeability of between about 4 and about 12 CU over at least 90% of the surface area of the wrapper.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the disclosure will now be described, by way of example only, with reference to accompanying drawings in which:

FIG. 1 illustrates a smoking article according to an embodiment;

FIG. 2 illustrates a smoking article according to a further embodiment, having a filter comprising a capsule;

FIG. 3 illustrates a smoking article according a further embodiment, having a filter comprising a tubular element; and

FIG. 4 illustrates a smoking article according a further embodiment, having a filter comprising a tubular element and adsorbent material dispersed within filter material.

DETAILED DESCRIPTION

The term “smoking article” as used herein is intended to refer to combustible smoking articles and their components such as cigarettes, cigarillos, cigars and roll-your-own cigarettes (whether based on tobacco, tobacco derivatives, expanded tobacco, reconstituted tobacco, tobacco substitutes or other smokable material).

Filters described herein can be provided to users as an integral component of a smoking article or as a discrete component separate from a smoking article. When provided separately, filter units and smoking articles can be packaged separately, or packaged together as a kit of parts.

Smoking articles such as cigarettes and their formats are often named according to the cigarette length: “regular” (typically in the range 68-75 mm, e.g. from about 68 mm to about 72 mm), “short” or “mini” (68 mm or less), “king-size” (typically in the range 75-91 mm, e.g. from about 79 mm to about 88 mm), “long” or “super-king” (typically in the range 91-105 mm, e.g. from about 94 mm to about 101 mm) and “ultra-long” (typically in the range from about 110 mm to about 121 mm).

They are also named according to the cigarette circumference: “regular” (about 23-25 mm), “wide” (greater than 25 mm), “slim” (about 22-23 mm), “demi-slim” (about 19-22 mm), “super-slim” (about 16-19 mm), and “micro-slim” (less than about 16 mm). Accordingly, a cigarette in a king-size, super-slim format will, for example, have a length of about 83 mm and a circumference of about 17 mm. Cigarettes in the regular, king-size format have a circumference of from 23 to 25 mm and an overall length of from 75 to 91 mm.

Each format may be produced with filters of different lengths, smaller filters being generally used in formats of smaller lengths and circumferences. In some examples, the filter length will be from about 15 mm, associated with short, regular formats, to 30 mm, associated with ultra-long super-slim formats. The tipping paper will have a greater length than the filter, for example from 3 to 10 mm longer, such that the tipping paper covers the filter and overlaps the tobacco rod to connect the filter to the tobacco rod.

Smoking articles and filters described herein can be made in, but are not limited to, any of the above formats.

The filter material forming the filters described herein can comprise cellulose acetate fibre tow. The filter material can also be formed using other materials used to form fibres, such as polyvinyl alcohol (PVOH), polylactic acid (PLA), polycaprolactone (PCL), poly(1-4 butanediol succinate) (PBS), poly(butylene adipate-co-terephthalate)(PBAT), starch based materials, paper, cotton, aliphatic polyester materials and polysaccharide polymers or a combination thereof. The filter material may be plasticised with a suitable plasticiser for the filter material, such as triacetin where the filter material is cellulose acetate tow, or may be non-plasticised. The tow used to produce the filter unit or other filter component can use any suitable specification, such as fibres having a ‘Y’ shaped or other cross section, filamentary denier values between 2.5 and 15 denier per filament, for example between 3.0 and 9.0 denier per filament and total denier values of 10,000 to 50,000, for example between 15,000 and 45,000.

As used herein, the terms “flavor” and “flavorant” refer to materials which, where local regulations permit, may be used to create a desired taste or aroma in a product for adult consumers. They may include extracts (e.g., liquorice, hydrangea, Japanese white bark magnolia leaf, chamomile, fenugreek, clove, menthol, Japanese mint, aniseed, cinnamon, herb, wintergreen, cherry, berry, peach, apple, Drambuie, bourbon, scotch, whiskey, spearmint, peppermint, lavender, cardamom, celery, cascarilla, nutmeg, sandalwood, bergamot, geranium, honey essence, rose oil, vanilla, lemon oil, orange oil, cassia, caraway, cognac, jasmine, ylang-ylang, sage, fennel, piment, ginger, anise, coriander, coffee, or a mint oil from any species of the genus Mentha), flavor enhancers, bitterness receptor site blockers, sensorial receptor site activators or stimulators, sugars or sugar substitutes (e.g., sucralose, acesulfame potassium, aspartame, saccharine, cyclamates, lactose, sucrose, glucose, fructose, sorbitol, or mannitol), and other substances or additives such as charcoal, chlorophyll, minerals, botanicals, or breath freshening agents. They may be imitation, synthetic or natural ingredients or blends thereof. They may be in any suitable form, for example, oil, liquid, or powder.

In the figures described herein, like reference numerals are used to illustrate equivalent features, articles or components.

FIG. 1 is a side-on cross sectional view of a smoking article 1. The smoking article 1, in the present example a cigarette, has a mouth end 1 a, arranged to be placed in the user's mouth when smoking, and a lit end 1 b, arranged to be lit when smoking. Tobacco material 2 is wrapped in a paper wrapper 3 to form a tobacco rod.

In some examples, the smoking article does not include a filter. In other examples, a filter 4 is connected to the tobacco rod, by a tipping paper 5. The filter 4 is wrapped in a plug wrap 6. A ventilation area 7 may be provided to allow external air into the filter 4 during use. The ventilation area may be provided as a series of perforations which pass through the tipping paper 5 and plug wrap 6 and into the filter 4.

The paper wrapper 3 has a diffusivity of between about 0.1 cm/s and 0.5 cm/s. In some examples, the paper wrapper 3 has a diffusivity of between about 0.1 cm/s and about 0.3 cm/s.

In some examples, the paper wrapper 3 has a diffusivity of less than about 0.30 cm/s. In some examples, the paper wrapper 3 has a diffusivity of less than 0.25 cm/s. In some examples, the paper wrapper 3 has a diffusivity of between 0.15 and 0.2 cm/s. Advantageously, such levels of diffusivity have been found to be particularly effective at providing smoking articles such as cigarettes with more consistent delivery per puff, and an increased number of puffs. Such smoking articles have also been found to pass the low ignition propensity tests known in the industry, while exhibiting acceptable rates of free air self-extinguishment. Free air self-extinguishment is the property of a smoking article to self-extinguish when held in free air (i.e. rather than being placed on a substrate), which is undesirable from a consumer's perspective. In some examples, the paper wrapper has a diffusivity of between 0.10 and 0.3 cm/s, between 0.15 and 0.25 cm/s, between 0.15 and 0.20 cm/s, or between 0.17 and 0.22 cm/s.

The paper wrapper 3 has a low permeability, in the present example a permeability of less than about 15 Coresta Units (CU). For instance, the paper wrapper can have a permeability of less than about 15 CU over at least 50% of the surface area of the paper wrapper, or over at least 75% or 90% of the surface area.

In some examples, the paper wrapper 3 has a permeability of between about 4 and about 12 CU. In some examples, the paper wrapper 3 has a permeability of between about 4 and about 12 CU over at least 90% of the surface area.

In some examples, the paper wrapper 3 has a permeability of less than 10 Coresta Units (CU), or between about 3 and about 7 CU, in each case over at least 50%, or more preferably 75% or 90% of the surface area of the paper wrapper.

In use of the smoking articles described herein, the paper wrapper 3 having the low diffusivity and low permeability ranges as described reduces the amount of oxygen drawn into the tobacco rod when the smoking article is smoked, as compared to smoking articles having paper wrappers with higher levels of diffusivity and permeability. Reducing the amount of oxygen drawn into the tobacco rod causes the tobacco 2 to burn at a slower rate between puffs, and thus has the effect of increasing the length of time over which the tobacco rod combusts, proving a longer smoking experience.

In some examples, the entire paper wrapper 3 has the low diffusivity and low permeability ranges defined herein.

In some examples, the diffusivity of the paper wrapper 3 may be uniform along the length of the tobacco rod when the paper wrapper 3 is wrapped around the tobacco rod. Additionally or alternatively, the diffusivity of the paper wrapper 3 may be uniform around the entire circumference of the tobacco rod. The paper wrapper 3 may include some areas having higher or lower diffusivity. In some examples, at least 50% of the paper wrapper is provided with a low diffusivity, for example, below 0.3 cm/s. In some examples, more than 75%, or 80% or about 100% of the wrapper is provided with a low diffusivity, for example, below 0.3 cm/s or below 0.25 cm/s. Alternatively or in addition, at least 50% of the paper wrapper can be provided with a low permeability, for example, below 15 CU. In some examples, more than 80%, 90%, or about 100% of the wrapper is provided with a low permeability as described, for example below 15 CU. The paper wrapper may have one or more discrete regions having low permeability and low diffusivity. In some examples, the entire paper wrapper is provided with a uniform low diffusivity and low permeability within the ranges described herein. Providing the entire paper wrapper with low diffusivity and low permeability reduces variability in free air self-extinguishment property of the smoking article for the duration of smoking compared to providing two or more discrete areas of the smoking article with low diffusivity and low permeability.

The filter 4 may be substantially cylindrical in shape. The filter 4 may be between 6 mm and 30 mm in length, for instance between 7 mm and 20 mm. In one example, the filter 4 is 18 mm in length.

The tobacco rod may also be substantially cylindrical in shape, with an external diameter substantially equal to the external diameter of the filter 4 if a filter is provided. The tobacco rod comprises a substantially cylindrical core of packed tobacco material 2 wrapped in the paper wrapper 3. The tobacco material 2 may comprise a blend of shredded tobacco, and may also include reconstituted tobacco material. The paper wrapper 3 extends around the circumference of the tobacco rod and extends along its length, to form a wrapped tobacco rod. The end faces of the tobacco rod are left open to allow a gaseous flow to pass axially through the rod.

In some embodiments, the tobacco rod includes tobacco having a net weight based on the size and type of the smoking article. For example, the tobacco weight may be a standard weight corresponding to a conventional smoking article of the same size. In some embodiments, the tobacco weight may be reduced compared to a conventional smoking article of the same size. The tobacco weight may be selected based on the desired characteristic of the smoking article. A lower tobacco weight may be associated with a reduction of staining of the paper wrapper. In addition, a lower tobacco weight may be associated with a reduction in the levels of CO and tar. However, a lower tobacco weight may also be associated with a reduction in puff number. Accordingly, the tobacco weight may be chosen according to the characteristic of the smoking article to be achieved.

In some examples, the smoking article may be a smoking article having a length of 90 mm and a circumference of 21 mm. The net tobacco weight may be, for example, 510 mg. In other examples, the smoking article may have a reduced tobacco weight of 480 mg. The smoking article having the reduced tobacco weight of 480 mg may include lower levels of CO and tar, and experience lower levels of staining on the paper wrapper. However, the puff number of the smoking article having the reduced tobacco weight of 480 mg may have a lower puff number when smoked by a user compared to a comparable smoking article having a net tobacco weight of 480 mg.

In other examples, a smoking article having a length of about 90 mm and a circumference of about 21 mm may include a tobacco weight of 490 mg. Alternatively the smoking article may include a reduced tobacco weight of about 460 mg.

In other examples, a smoking article having a length of about 90 mm and a circumference of about 23 mm may include a tobacco weight of around 630 mg. Alternatively, the smoking article may include a reduced tobacco weight of about 560 mg.

It will be apparent to the skilled person that the tobacco weight may be selected based on these characteristics of the resulting smoking article, for example by selecting a lower tobacco weight in order to reduce staining and CO and tar levels, or by selecting a higher tobacco weight to increase the number of puffs than can be obtained on smoking.

During use, in which the smoking article 1 is smoked by a user, air is drawn through the lit tobacco rod to provide smoke to the user. In embodiments including a filter, the smoke is also drawn through the filter to remove some particulate material from the smoke before it is provided to the user. In embodiments including a ventilated filter, during use air is drawn through the ventilation area 7 of the filter 4 in order to dilute the smoke delivered to the user through the filter 4.

In some examples, the ventilation area 7 comprises perforations in the filter tipping paper 5 and plug wrap 6. In some examples, the ventilation area 7 comprises embossed regions in the filter tipping paper 5 or plug wrap 6. At least one of the tipping paper 5 and plug wrap 6 can alternatively be provided as a porous material, for instance having a porosity greater than 200 Coresta Units, allowing air into the filter 4. The filter 4 may be vented by vent channels formed using laser or electrostatic perforation techniques. The ventilation area 7 can be provided into any part of the filter 4, for instance a part at least 12 mm from the mouth end 1 a of the smoking article. In examples having multiple filter sections or segments, the ventilation area can, for instance, be provided into a filter section or segment adjacent to the tobacco rod.

In some examples, the pressure drop across the filter 4 is between 40 mm Water Gauge (WG) and 180 mm WG. The pressure drop of the filter may be selected depending on the desired characteristics of the product. In some examples, the pressure drop across the filter is between 70 mmWG and 180 mmWG. In some examples, the pressure drop across the filter is between 130 mmWG and 180 mmWG. In some examples, the pressure drop across the filter is between 140 mmWG and 180 mmWG. In some examples, the pressure drop across the filter is between 70 mmWG and 100 mmWG. In some examples, the pressure drop across the filter is between 85 mmWG and 100 mmWG.

In some examples, filter is not provided with a ventilation area. In other examples, the filter is provided with a ventilation area. The ventilation area 7 of the filter 4 may provide between 40% and 90% ventilation when the smoking article is smoked in use. The ventilation area can, for instance, provide between 55% and 90% ventilation. In some examples, the ventilation area provides between 55% and 85% ventilation. In some examples, the ventilation area provides between 60% and 75% ventilation. In some examples, the ventilation area provides between 65% and 75% ventilation.

By changing the levels of ventilation and the pressure drop across the filter, the levels of CO and tar delivered to the user may be altered. A higher ventilation level across the filter results in the levels of tar and CO being reduced when using the cigarette paper with low diffusivity and low permeability as described herein. A higher level of ventilation also increases the number of puffs during smoking. However, a lower ventilation level across the filter reduces the likelihood of the smoking article to self-extinguish in free air during smoking. Therefore, the ventilation level may be selected according to these properties of the smoking article.

In some examples, the paper wrapper surrounding the tobacco rod has a basis weight of between 24 and 36 g/m². The weight of the paper is one of the factors which may influence the diffusivity of the paper. An increased weight per square metre of the paper increases the diffusivity of the paper. Therefore, in order to provide a low diffusivity for the wrapper, the weight of the paper is selected to be between 24 and 36 g/m². In some examples, the paper surrounding the tobacco rod has a weight between 27 and 32 g/m². In some examples, the paper surrounding the tobacco rod has a weight of about 28 g/m². In some examples, the paper surrounding the tobacco rod has a weight of about 32 g/m². Higher weight per square metre of the paper wrapper 3 may also provide for increased opacity of the paper wrapper. Increasing the basis weight of the paper together with increasing the diffusivity of the paper reduces the level of staining of the cigarette paper during smoking.

In some examples, the paper may comprise a filler. In some examples, the filler content of the paper wrapper 3 is less than 30% by weight of the paper. In some examples, the filler content of the paper wrapper is between 15 and 25% by weight. A lower filler content decreases the diffusion capacity of the paper wrapper and so may also lead to increased LIP (low ignition propensity) pass rates. In addition, using lower filler content may increase the number of puffs achievable when the smoking article is smoked in use. The filler content of the paper wrapper may be above 15%. In some examples, the filler content of the paper wrapper may be between 21 and 22% by weight. In some examples, the filler is calcium carbonate. However, it will be recognised that any other suitable filler may be used. It will be recognised that the amount of the filler used may be selected by the skilled person in order to achieve desired characteristics such as, but not limited to, diffusivity, puff number, opacity, smoke yield and LIP pass rate.

The opacity of the paper may be affected by the particle size of the filler used. For example, smaller particle sizes may result in higher opacity. In some examples, the particle size may be between 0.3 μm and 2 μm. The opacity may also be affected by the structure of the filler. For example, when calcium carbonate is used as the filler, it may comprise, but is not limited to, calcite crystal, precipitated calcium carbonate, or ground calcium carbonate.

In some examples, the paper wrapper comprises a burn additive. In some examples, the paper wrapper comprises less than 4% burn additive by weight. The burn additive decreases the likelihood that the smoking article will self-extinguish in free air, that is, for example, when the user is holding the smoking article between puffs. However, increasing the level of burn additive may decrease the LIP pass rate of the smoking article. In some examples, the paper wrapper comprises 1% burn additive by weight. In some examples, the burn additive is tri-potassium citrate. In some examples, the burn additive is tri-sodium citrate. In some examples, the burn additive comprises tri-sodium citrate and tri-potassium citrate. However, it will be recognised that any suitable burn additive may be used. The amount of burn additive may be selected by the skilled person in order to achieve desired characteristics such as, but not limited to, smoke yield and LIP pass rate.

In some examples, the filter comprises filter material having a denier per filament of between about 2.5 and about 9, for instance between about 3 and about 8.

In some examples, the filter comprises filter material having a total denier of between about 10,000 and about 32,000, for instance between about 12,000 and about 30,000.

FIG. 2 illustrates a smoking article 1′ according to a further embodiment, the smoking article 1′ being the same as the smoking article 1 of FIG. 1 except having a filter 4 comprising a capsule 8. In the present example, the filter 4 is formed from filter material, in the present case cellulose acetate tow treated with a plasticiser, in the present case triacetin. The capsule 8 is spherical and has a diameter of 3.5 mm, although other shapes and sizes of capsule can be used, for instance a capsule having a diameter of about 3 mm, or between 0.5 mm and 6 mm, or between 2 mm and 5 mm. The capsule 8 is embedded within and surrounded on all sides by the filter material of the filter 4. The capsule 8 contains a fluid additive which modifies properties of mainstream smoke passing through the smoking article 11. The capsule 8 can be manufactured and inserted into the filter 4 using existing processes and machinery. In the present example, the capsule 8 contains menthol flavorant, although other fluids or granular additives could be contained within the capsule 8. The capsule can be ruptured by a consumer squeezing the filter to release the fluid additive into the filter material of the filter 4. The filter 4 of FIG. 2 may be between 7 mm and 30 mm in length, for instance between 7 mm and 20 mm. In one example, the filter 4 is 18 mm in length.

FIG. 3 illustrates a smoking article 1″ according a further embodiment, the smoking article 1″ being the same as the smoking article 1 of FIG. 1, except having a filter section 4 a similar to the filter 4 of FIG. 1 connected coaxially to a tubular element 4 b. The tubular element 4 b is formed from fibrous filter material in the present example. The fibrous filter material is, in the present example, continuous cellulose acetate tow plasticised with triacetin. A channel extends lengthwise through the centre of the tubular element 4 b. The channel extending through the centre of the filter element 4 b can be from 1 mm to 6 mm in diameter, for instance from 2 mm to 5 mm in diameter. The tubular element 4 b may be a non-wrapped element or may be wrapped in a plug wrap (not shown). The filter section 4 a may also be non-wrapped or wrapped in a plug wrap (not shown), and a combining plug wrap 10 may be used to connect the tubular element 4 b and filter section 4 a. The filter section 4 a may be between 6 mm and 30 mm in length, for instance between 6 mm and 20 mm. In one example, the filter section 4 a is 12 mm or 18 mm in length. The hollow tubular element 4 b may be between 6 mm and 15 mm in length, for instance between 6 mm and 12 mm or in one example 7 mm in length.

FIG. 4 illustrates a smoking article 1′″ according a further embodiment, the smoking article 1′″ being the same as the smoking article 1″ of FIG. 3, except having a filter segment 4 c including an adsorbent material 9 dispersed within filter material upstream of the filter section 4 a. A combining plug wrap 10 may be used to connect the tubular element 4 b, filter section 4 a and filter segment 4 c. The adsorbent material 9 is, in the present example, provided in the form of activated carbon particles, although other forms of adsorbent can be used, such as ion exchange resins. The filter section 4 c may be between 6 mm and 20 mm in length, for instance between 6 mm and 18 mm or in one example 12 mm in length.

In a method of manufacturing a smoking article, for instance a smoking article as described herein, in a first step a tobacco rod is formed by wrapping tobacco material in a paper wrapper having a diffusivity of between about 0.1 cm/s and 0.5 cm/s and a permeability of less than about 15 CU. In a second step, a filter may be attached to the tobacco rod. In a third step, a ventilation area may be provided for allowing ventilation into the filter.

In some examples of the method, the paper wrapper has a diffusivity of between about 0.1 cm/s and 0.3 cm/s. In some examples, the paper wrapper has a permeability of between about 4 and about 12 CU over at least 50% of the surface area of the wrapper. In some examples, the paper wrapper has a permeability of between about 4 and about 12 CU over at least 90% of the surface area of the wrapper.

Examples of smoking articles in accordance with embodiments are described below. Unless specified otherwise, testing of the smoking articles was carried out according to ISO 3308:2000, in which a 35 ml puff of 2 s duration is taken every 60 s.

Example 1

An exemplary cigarette was produced having the filter arrangement as illustrated in FIG. 4 and a circumference of about 23.4 mm. The net weight of tobacco in the tobacco rod was 560 mg/cigarette. The paper wrapper basis weight was 28 g/m². The burn additive level was 1%. The total filter length was 34 mm, connected to a tobacco rod having a length of 56 mm giving a total cigarette length of 90 mm. The tip ventilation was arranged to be about 68%. The pressure drop across the filter was about 100 mmWG. The number of puffs achieved using these parameters was about 9.5 delivering about 5 mg of tar.

Example 2

An exemplary cigarette was produced having the filter arrangement as illustrated in FIG. 4 and a circumference of about 23.4 mm. The net weight of tobacco in the tobacco rod was 630 mg/cigarette. The paper wrapper basis weight was 28 g/m². The burn additive level was 1%. The total filter length was 27 mm, connected to a tobacco rod having a length of 63 mm giving a total cigarette length of 90 mm. The tip ventilation was arranged to be about 67%. The pressure drop across the filter was about 90 mmWG. The number of puffs achieved using these parameters was about 11 delivering about 7 mg of tar.

Example 3

An exemplary cigarette was produced having the filter arrangement as illustrated in FIG. 4 and a circumference of about 21 mm. The paper wrapper basis weight was 28 g/m². The burn additive level was 1%. The total filter length was 27 mm, connected to a tobacco rod having a length of 63 mm giving a total cigarette length of 90 mm. The tip ventilation was arranged to be about 72%. The pressure drop across the filter was about 177 mmWG. The number of puffs achieved using these parameters was about 10.3 delivering about 6.1 mg of tar.

The various embodiments described herein are presented only to assist in understanding and teaching the claimed features. These embodiments are provided as a representative sample of embodiments only, and are not exhaustive or exclusive. It is to be understood that advantages, embodiments, examples, functions, features, structures, or other aspects described herein are not to be considered limitations on the scope of the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope of the disclosure. Various embodiments of the disclosure may suitably comprise, consist of, or consist essentially of, appropriate combinations of the disclosed elements, components, features, parts, steps, means, etc, other than those specifically described herein. In addition, this disclosure may include other embodiments not presently claimed, but which may be claimed in future. 

1. A smoking article comprising: tobacco material wrapped in a paper wrapper to form a tobacco rod; and wherein the paper wrapper has a diffusivity of between about 0.1 cm/s and 0.5 cm/s and a permeability of less than about 15 CU.
 2. The smoking article according to claim 1, wherein the paper wrapper has a diffusivity of between about 0.1 cm/s and 0.3 cm/s.
 3. The smoking article according to claim 1, wherein the paper wrapper has a diffusivity of between about 0.15 and about 0.25, between about 0.15 and about 0.20, or between about 0.17 and about 0.22 cm/s.
 4. The smoking article according to claim 1, wherein the paper wrapper has a permeability of less than about 15 CU over at least 50% of the surface area of the paper wrapper.
 5. The smoking article according to claim 4, wherein the paper wrapper has a permeability of between about 4 and about 12 CU.
 6. The smoking article according to claim 4, wherein the paper wrapper has a permeability of between about 4 and about 12 CU over at least 90% of the surface area of the paper wrapper.
 7. The smoking article according to claim 1, wherein the paper wrapper has a permeability of less than about 10 CU, or between about 3 and about 7 CU, over at least 90% of the surface area of the paper wrapper.
 8. The smoking article according to claim 1, further comprising a filter.
 9. The smoking article according to claim 8, wherein a pressure drop across the filter is between about 40 mm water gauge (WG) and 180 mm WG.
 10. The smoking article according to claim 8, wherein the filter comprises a ventilation area.
 11. The smoking article according to claim 10, wherein the ventilation area provides ventilation of between 40% and 90%.
 12. The smoking article according to claim 8, wherein the filter comprises filter material having a denier per filament of between 2.5 and
 9. 13. The smoking article according to claim 8, wherein the filter comprises filter material having a total denier of between 10,000 and 32,000.
 14. The smoking article according to claim 1, wherein the paper wrapper has a basis weight of between 24 and 36 g/m².
 15. The smoking article according to claim 14, wherein the paper wrapper has a basis weight of between 27 and 32 g/m².
 16. The smoking article according to claim 15, wherein the paper wrapper has a basis weight of about 28 g/m².
 17. The smoking article according to claim 15, wherein the paper wrapper has a basis weight of about 32 g/m².
 18. The smoking article according to claim 1, wherein the paper wrapper includes less than 30% filler by weight of the paper wrapper.
 19. The smoking article according to claim 18, wherein the paper wrapper includes between 15 and 25% filler by weight.
 20. The smoking article according to claim 18, wherein the filler comprises calcium carbonate.
 21. The smoking article according to claim 1, wherein the paper wrapper has an opacity of between 60% and 80%, or between 68% and 80%.
 22. The smoking article according to claim 1, wherein the paper wrapper comprises less than 4% burn additive by weight of the paper wrapper.
 23. The smoking article according to claim 22, wherein the paper wrapper comprises about 1% burn additive by weight.
 24. The smoking article according to claim 22, wherein the burn additive is sodium citrate, potassium citrate, or a mixture of sodium citrate and potassium citrate.
 25. A method of manufacturing a smoking article, the method comprising: forming a tobacco rod by wrapping tobacco material in a paper wrapper having a diffusivity of between about 0.1 cm/s and 0.5 cm/s and a permeability of less than about 15 CU.
 26. The method of manufacturing a smoking article according to claim 25, further comprising a filter to said tobacco rod.
 27. The method of manufacturing a smoking article according to claim 26, further comprising providing a ventilation area for allowing ventilation into said filter.
 28. The method of manufacturing a smoking article according to claim 25, wherein the paper wrapper has a diffusivity of between about 0.1 cm/s and 0.3 cm/s.
 29. The method of manufacturing a smoking article according to claim 25, wherein the paper wrapper has a permeability of between about 4 and about 12 CU over at least 50% of the surface area of the wrapper.
 30. The method of manufacturing a smoking article according to claim 25, wherein the paper wrapper has a permeability of between about 4 and about 12 CU over at least 90% of the surface area of the wrapper. 